Nonwoven fabrics and their manufacture have been the subject of extensive development resulting in a wide variety of materials for numerous applications. For example, nonwovens of light basis weight and open structure are used in personal care items such as disposable diapers as liner fabrics that provide dry skin contact but readily transmit fluids to more absorbent materials which may also be nonwovens of a different composition and/or structure. Nonwovens of heavier weights may be designed with pore structures making them suitable for filtration, absorbent and barrier applications such as wrappers for items to be sterilized, wipers or protective garments for medical, veterinary or industrial uses. Even heavier weight nonwovens have been developed for recreational, agricultural and construction uses. These are but a few of the practically limitless examples of types of nonwovens and their uses that will be known to those skilled in the art who will also recognize that new nonwovens and uses are constantly being identified. There have also been developed different ways and equipment to make nonwovens having desired structures and compositions suitable for these uses. Examples of such processes include spunbonding, meltblowing, carding, and others which will be described in greater detail below. One type of process for manufacturing nonwovens is conjugate or bicomponent spinning. The present invention has general applicability to bicomponent sheath/core nonwovens as will be apparent to one skilled in the art, and it is not to be limited by reference or examples relating to specific nonwovens which are merely illustrative.
It is not always possible to efficiently produce a nonwoven having all the desired properties as formed, and it is frequently necessary to combine the nonwoven with one or more component layers of the same or different construction or composition. Examples include other nonwovens or films which can improve properties such as barrier and strength. The success of such laminates is often dependent on the ability to provide strong interlayer bonding or peel strength to prevent unintended separation into component layers. The type of bonding is important for commercial and functional reasons, and various means have been employed such as heat, heat and pressure, pressure, adhesives and mechanical steps such as entangling or the like. For many applications a combination of heat and pressure, for example hot calendering, provides the best combination of function and efficiency. However, for some applications it is desired to improve the peel strength in such laminates bonded by heat and pressure.